Method for the preparation of a poly (arylene ether)-polyolefin composition, and composition prepared thereby

ABSTRACT

A poly(arylene ether)-polyolefin composition is prepared by melt-blending a poly(arylene ether) and a compatibilizer to form a first blend, and melt-blending the first blend and a polyolefin to form a second blend. The composition lacks an unhydrogenated block copolymer, a poly(alkenyl aromatic) resin, or both. Multiple mixing elements, low throughput, and high extruder rotations per minute may be used to achieve high energy mixing of the first and second blends. Compositions prepared by the method exhibit an improved balance of impact strength, stiffness, and heat resistance, as well as reduced variability of physical properties.

CROSS REFERENCE TO RELATED APPLICATION

This application is a division of U.S. Nonprovisional application Ser.No. 10/754,126 filed 9 Jan. 2004.

BACKGROUND

Poly(arylene ether)-polyolefin compositions are well known. Manyreferences teach the desirability of preparing these compositions bycombining all components in a single mixing step. See, for example, U.S.Pat. No. 4,764,559 to Yamauchi et al.; U.S. Pat. No. 4,772,657 toAkiyama et al.; U.S. Pat. No. 4,863,997 to Shibuya et al.; U.S. Pat. No.4,985,495 to Nishio et al.; U.S. Pat. No. 4,990,558 to DeNicola, Jr. etal.; U.S. Pat. Nos. 5,071,912, 5,075,376, 5,132,363, 5,159,004,5,182,151, and 5,206,281 to Furuta et al.; U.S. Pat. No. 5,418,287 toTanaka et al., and European Patent Application No. 412,787 A2 to Furutaet al.

Alternatively, some references teach the desirability of addingcomponents in order of higher to lower viscosities. See, for example,U.S. Pat. No. 4,764,559 to Yamauchi et al., 4,985,495 to Nishio et al.,and U.S. Pat. No. 5,418,287 to Tanaka et al.

In yet another proposed blending method, a polyphenylene ether and apolypropylene-graft-polystyrene copolymer, with or without unmodifiedpolypropylene, are pre-mixed before one or more rubbery substances areadded with additional mixing. See, for example, U.S. Pat. Nos.5,071,912, 5,075,376, 5,132,363, 5,159,004, 5,182,151, and 5,206,281 toFuruta et al.; European Patent Application No. 412,787 A2 to Furuta etal.; and Japanese Unexamined Patent Application 63[1988]-113049 toShibuya et al.

The above-described methods produce compositions that are inadequate formany commercial uses because they exhibit excessive variability in keyproperties, including stiffness and impact strength. There remains aneed for a method of producing poly(arylene ether)-polyolefincompositions having improved property balances. In particular, thereremains a need for a method of producing poly(arylene ether)-polyolefincompositions exhibiting reduced property variability and improvedtradeoffs between stiffness, impact strength, and heat resistance.

BRIEF SUMMARY

The above described and other drawbacks and disadvantages of the priorart are alleviated by a method of preparing a thermoplastic composition,comprising: melt-blending a poly(arylene ether) and a compatibilizer toform a first intimate blend; and melt-blending the first intimate blendand a polyolefin to form a second intimate blend; wherein thethermoplastic composition is substantially free of at least onecomponent selected from (a) an unhydrogenated block copolymer of analkenyl aromatic compound and a conjugated diene, and (b) a poly(alkenylaromatic) resin.

Additional embodiments are described in detail below.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a diagrammatic view of kneading blocks used in high and lowintensity upstream and downstream kneading.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

One embodiment is a method comprising: melt-blending a poly(aryleneether) and a compatibilizer to form a first intimate blend; andmelt-blending the first intimate blend and a polyolefin to form a secondintimate blend; wherein the thermoplastic composition is substantiallyfree of at least one component selected from (a) an unhydrogenated blockcopolymer of an alkenyl aromatic compound and a conjugated diene, and(b) a poly(alkenyl aromatic) resin.

Extensive experiments by the present inventors have led to thesurprising observation that the properties of the composition preparedaccording to this method are substantially and unexpectedly improvedcompared to compositions prepared by known methods, especially thosemethods in which all components are blended simultaneously.

In a preferred embodiment, melt-blending to form the first intimateblend comprises high-energy mixing. The energy of mixing may beexpressed in various ways. One factor contributing to the energy ofmixing is the extruder addition point. For example, when the compositionis compounded on an eleven barrel twin-screw extruder, high-energymixing of the first-intimate blend may be expressed as addition of firstintimate blend components to one of the first four barrels.

Another factor contributing to the energy of mixing is the number ofmixing sections, with greater numbers of mixing sections correspondingto higher energy mixing. Each mixing section may comprise at least onemixing element. The first intimate blend and the second intimate blendare each preferably formed using at least one mixing section. Mixingsections and mixing elements are generally well known in the art ascomponents of twin-screw extruders. Each mixing element is disposednon-rotatably on a screw shaft and is used to disperse and distributecomponents of a thermoplastic composition throughout the blend. Themixing element may or may not advance the composition toward the outletof the extruder. The present inventors have found that the properties ofthe composition are improved if the processes of mixing to form thefirst intimate blend and the second intimate blend each employ at leastone mixing section. In a preferred embodiment, mixing to form the firstintimate blend and the second intimate blend each employ at least twomixing elements on each screw shaft.

There is no particular limitation on the design of the individual mixingelements. Suitable mixing elements include, for example, mixing elementson each of said shafts which are in radial interwiping relation withinthe extruder barrel and configured to wipe one another and the cylinderwalls, as described in U.S. Pat. No. 4,752,135; mixing element diskshaving mixing wings as described in U.S. Pat. No. 3,195,868 to Loomanset al. and U.S. Pat. No. 5,593,227 to Scheuring et al.; mixing elementshaving two opposing lobes wherein one lobe is tapered, as described inU.S. Pat. No. 6,116,770 to Kiani et al.; and the various mixingelements, including those characterized as prior art mixing elements,described in U.S. Pat. No. 5,932,159 to Rauwendaal.

In one embodiment, melt-blending to form a first intimate blend andmelt-blending to form a second intimate blend collectively comprisemixing with a mixing energy input of at least about 0.20kilowatt-hour/kilogram (kW-hr/kg). A mixing energy input of at leastabout 0.22 kW-hr/kg may be preferred, and an energy input of at leastabout 0.24 kW-hr/kg may be more preferred. Such quantitative mixingenergy input may be determined by measuring the rotation rate of theextruder motor and the extruder motor's current draw. Since a directcurrent (DC) motor speed is directly proportional to the voltageapplied, a previously measured proportionality constant may be used toconvert the measured motor speed, in rpm, to a voltage in volts. Theenergy input may then be calculated as the product of the extruder motorcurrent and voltage, divided by the extruder throughput rate. Forexample, an extruder operating at 120 volts, 2 amps, and a throughput of1 kg/hr has an energy input of(120 V)(2 A)/(1 kg/hr)=240 W-hr/kgor 0.240 kW-hr/kg.

In one embodiment, the first intimate blend may be formed and pelletizedin one step, then mixed with the polyolefin to form the second intimateblend in another step.

Suitable temperatures for forming the composition are generally about180° C. to about 400° C. Within this range it may be preferred to formthe first intimate blend by exposing the first intimate blend componentsto a temperature of at least about 200° C., more preferably at leastabout 250° C., yet more preferably at least about 280° C. Also withinthe above range, it may be preferred to form the first intimate blend byexposing the first intimate blend components to a temperature of up toabout 320° C., more preferably up to about 300° C., yet more preferablyup to about 290° C. The same temperatures are also suitable forformation of the second intimate blend.

The method is suitable for preparing the poly(arylene ether)-polyolefincompositions on any scale, from grams to tons. For economical productionof commercially significant amounts of the composition, it may preferredthat the method have a throughput rate of at least about 10 kilogramsper hour (kg/h), more preferably at least about 5,000 kg/h, based on thetotal weight of the composition. Throughput rates of 100,000 kg/h andhigher may be used.

Any known apparatus may be used to carry out the method. Utilization ofthe method on a laboratory scale may employ a lab-scale mixer such as,for example, a Labo Plastomill available from Toyo Seiki Company, Hyogo,Japan. Preferred apparatuses for conducting the method on a larger scaleinclude single-screw and twin-screw extruders, with twin-screw extrudersbeing more preferred. Extruders for melt blending of thermoplastics arecommercially available from, for example, Coperion, Ramsey, N.J. Themethod may also be carried out using apparatus designed to compound thecomposition and mold it directly, without an intermediate pelletizingstep. Such apparatus is described, for example, in U.S. Pat. No.6,109,910 to Sekido, and 6,464,910 B1 to Smorgon et al; U.S. PatentApplication No. 2003/0021860 A1 to Clock et al; and InternationalPublication No. WO 02/43943 A1 to Adedeji et al.

FIG. 1 illustrates non-limiting examples of extruder configurationsuseful for conducting the method. The upper half of the figure is a fullextruder configuration using high intensity (“+1”) upstream kneading(“kneading 1”) and low intensity (“−1”) downstream kneading (“kneading2”). High intensity upstream and downstream kneading correspond to useof assemblies of multiple right-handed, left-handed, and neutralkneading elements as depicted in FIG. 1 as Kneading 1 (+1) and Kneading2 (+1), respectively. Likewise, low intensity upstream and downstreamkneading corresponded to the use of assemblies depicted in FIG. 1 asKneading 1 (−1) and Kneading 2 (−1), respectively. In the screw elementslabeled in FIG. 1, RSE stands for right-handed screw element, SFE standsfor single flighted element, RKB stands for right-handed kneading block,NKB stands for neutral kneading block, and LKB stands for left-handedkneading block. Each labeled element includes a two-number orthree-number designation following the three letter acronyms describedabove. For conveying elements (i.e., those elements for which the thirdletter of the three letter acronym is “E”), the first number is thepitch (i.e., the axial length in millimeters required for a flight tomake a full revolution). For kneading blocks (i.e., those elements forwhich the third letter of the three letter acronym is “B”), the firstnumber is the offset angle of each individual disk to its neighbor, andthe second number is the total number of disks that make up the screwelement. For all screw elements, the last number is the total length ofthe screw element in millimeters. The numbered sections above the screwelements are known as barrel numbers. Each kneading section is boundedby the first and last kneading blocks within that section. For example,“Kneading 1 +1” is bounded on the left by RKB 45/5/28 and on the rightby LKB 45/5/14. It will be understood that the lower half of the figureis meant to show the “opposite” versions of Kneading 1 and Kneading 2that may be inserted into the corresponding kneading sections in theupper half of the figure.

The first intimate blend may comprise any conventional poly(aryleneether). The term poly(arylene ether) includes polyphenylene ether (PPE)and poly(arylene ether) copolymers; graft copolymers; poly(aryleneether) ether ionomers; and block copolymers of alkenyl aromaticcompounds, vinyl aromatic compounds, and poly(arylene ether), and thelike; and combinations comprising at least one of the foregoing; and thelike. Poly(arylene ether)s are known polymers comprising a plurality ofstructural units of the formula:

wherein for each structural unit, each Q¹ is independently halogen,primary or secondary C₁-C₈ alkyl, phenyl, C₁-C₈ haloalkyl, C₁-C₈aminoalkyl, C₁-C₈ hydrocarbonoxy, or C₂-C₈ halohydrocarbonoxy wherein atleast two carbon atoms separate the halogen and oxygen atoms; and eachQ² is independently hydrogen, halogen, primary or secondary C₁-C₈ alkyl,phenyl, C₁-C₈ haloalkyl, C₁-C₈ aminoalkyl, C₁-C₈ hydrocarbonoxy, orC₂-C₈ halohydrocarbonoxy wherein at least two carbon atoms separate thehalogen and oxygen atoms. Preferably, each Q¹ is alkyl or phenyl,especially C₁-C₄ alkyl, and each Q² is independently hydrogen or methyl.

Both homopolymer and copolymer poly(arylene ether)s are included. Thepreferred homopolymers are those comprising 2,6-dimethylphenylene etherunits. Suitable copolymers include random copolymers comprising, forexample, such units in combination with 2,3,6-trimethyl-1,4-phenyleneether units or copolymers derived from copolymerization of2,6-dimethylphenol with 2,3,6-trimethylphenol. Also included arepoly(arylene ether)s containing moieties prepared by grafting vinylmonomers or polymers such as polystyrenes, as well as coupledpoly(arylene ether) in which coupling agents such as low molecularweight polycarbonates, quinones, heterocycles and formals undergoreaction in known manner with the hydroxy groups of two poly(aryleneether) chains to produce a higher molecular weight polymer. Poly(aryleneether)s of the present invention further include combinations of any ofthe above.

The poly(arylene ether) generally has a number average molecular weightof about 3,000 to about 40,000 atomic mass units (AMU) and a weightaverage molecular weight of about 6,000 to about 80,000 AMU, asdetermined by gel permeation chromatography. The poly(arylene ether)generally may have an intrinsic viscosity of about 0.1 to about 0.6deciliters per gram (dL/g) as measured in chloroform at 25° C. Withinthis range, the intrinsic viscosity may preferably be at least about 0.2dL/g, more preferably at least about 0.3 dL/g. Also within this range,the intrinsic viscosity may preferably be up to about 0.5 dL/g, morepreferably up to about 0.47 dL/g. It is also possible to utilize a highintrinsic viscosity poly(arylene ether) and a low intrinsic viscositypoly(arylene ether) in combination. Determining an exact ratio, when twointrinsic viscosities are used, will depend on the exact intrinsicviscosities of the poly(arylene ether)s used and the ultimate physicalproperties desired.

The poly(arylene ether)s are typically prepared by the oxidativecoupling of at least one monohydroxyaromatic compound such as2,6-xylenol or 2,3,6-trimethylphenol. Catalyst systems are generallyemployed for such coupling; they typically contain at least one heavymetal compound such as a copper, manganese or cobalt compound, usuallyin combination with various other materials.

Particularly useful poly(arylene ether)s for many purposes include thosethat comprise molecules having at least one aminoalkyl-containing endgroup. The aminoalkyl radical is typically located in an ortho positionrelative to the hydroxy group. Products containing such end groups maybe obtained by incorporating an appropriate primary or secondarymonoamine such as di-n-butylamine or dimethylamine as one of theconstituents of the oxidative coupling reaction mixture. Also frequentlypresent are 4-hydroxybiphenyl end groups, typically obtained fromreaction mixtures in which a by-product diphenoquinone is present,especially in a copper-halide-secondary or tertiary amine system. Asubstantial proportion of the polymer molecules, typically constitutingas much as about 90% by weight of the polymer, may contain at least oneof the aminoalkyl-containing and 4-hydroxybiphenyl end groups.

The first intimate blend may comprise poly(arylene ether) in an amountof about 10 to about 70 weight percent, based on the total weight of thecomposition. Within this range, it may be preferred to use at leastabout 15 weight percent, more preferably at least about 20 weightpercent, of the poly(arylene ether). Also within this range, it may bepreferred to use up to about 60 weight percent, more preferably up toabout 50 weight percent, still more preferably up to about 40 weightpercent, of the poly(arylene ether).

The first intimate blend further comprises a compatibilizer. While notwishing to be bound by any particular hypothesis, the present inventorsbelieve that the compatibilizer acts to stabilize the interface betweenthe poly(arylene ether) phase and the polyolefin phase. Suitablecompatibilizers include, for example, hydrogenated block copolymers ofan alkenyl aromatic compound and a conjugated diene compound, partiallyhydrogenated block copolymers of an alkenyl aromatic compound and aconjugated diene compound, polyolefin-poly(alkenyl aromatic) copolymers,polyolefin-poly(arylene ether) graft copolymers, polyolefin-poly(aryleneether) block copolymers, and the like, and mixtures thereof.

The compatibilizer may be a hydrogenated block copolymer of an alkenylaromatic compound and a conjugated diene. The hydrogenated blockcopolymer is a copolymer comprising (A) at least one block derived froman alkenyl aromatic compound and (B) at least one block derived from aconjugated diene, in which the aliphatic unsaturated group content inthe block (B) is reduced by hydrogenation. The arrangement of blocks (A)and (B) includes a linear structure and a so-called radial teleblockstructure having branched chains.

Preferred of these structures are linear structures embracing diblock(A-B block), triblock (A-B-A block or B-A-B block), tetrablock (A-B-A-Bblock), and pentablock (A-B-A-B-A block or B-A-B-A-B block) structuresas well as linear structures containing 6 or more blocks in total of Aand B. More preferred are diblock, triblock, and tetrablock structures,with the A-B diblock and A-B-A triblock structures being particularlypreferred.

The alkenyl aromatic compound providing the block (A) is represented byformula:

wherein R² and R³ each independently represent a hydrogen atom, a C₁-C₈alkyl group, a C₂-C₈ alkenyl group, or the like; R⁴ and R⁸ eachindependently represent a hydrogen atom, a C₁-C₈ alkyl group, a chlorineatom, a bromine atom, or the like; and R⁵-R⁷ each independentlyrepresent a hydrogen atom, a C₁-C₈ alkyl group, a C₂-C₈ alkenyl group,or the like, or R⁴ and R⁵ are taken together with the central aromaticring to form a naphthyl group, or R⁵ and R⁶ are taken together with thecentral aromatic ring to form a naphthyl group.

Specific examples, of the alkenyl aromatic compounds include styrene,p-methylstyrene, alpha-methylstyrene, vinylxylenes, vinyltoluenes,vinylnaphthalenes, divinylbenzenes, bromostyrenes, chlorostyrenes, andthe like, and combinations comprising at least one of the foregoingalkenyl aromatic compounds. Of these, styrene, alpha-methylstyrene,p-methylstyrene, vinyltoluenes, and vinylxylenes are preferred, withstyrene being more preferred.

Specific examples of the conjugated diene include 1,3-butadiene,2-methyl-1,3-butadiene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, andthe like. Preferred among them are 1,3-butadiene and2-methyl-1,3-butadiene, with 1,3-butadiene being more preferred.

In addition to the conjugated diene, the hydrogenated block copolymermay contain a small proportion of a lower olefinic hydrocarbon such as,for example, ethylene, propylene, 1-butene, dicyclopentadiene, anon-conjugated diene, or the like.

There is no particular restriction on the content of the repeating unitderived from the alkenyl aromatic compound in the hydrogenated blockcopolymer. Suitable alkenyl aromatic content may be about 10 to about 90weight percent based on the total weight of the hydrogenated blockcopolymer. Within this range, it may be preferred to have an alkenylaromatic content of at least about 40 weight percent, more preferably atleast about 50 weight percent, yet more preferably at least about 55weight percent. Also within this range, it may be preferred to have analkenyl aromatic content of up to about 85 weight percent, morepreferably up to about 75 weight percent.

There is no particular limitation on the mode of incorporation of theconjugated diene in the hydrogenated block copolymer backbone. Forexample, when the conjugated diene is 1,3-butadiene, it may beincorporated with about 1% to about 99% 1,2-incorporation with theremainder being 1,4-incorporation.

The hydrogenated block copolymer is preferably hydrogenated to such adegree that less than 20%, yet more preferably less than 10%, of thealiphatic unsaturation in the aliphatic chain moiety derived from theconjugated diene remains unreduced. The aromatic unsaturated bondsderived from the alkenyl aromatic compound may be hydrogenated to adegree of up to about 25%.

The hydrogenated block copolymer preferably has a number averagemolecular weight of about 5,000 to about 500,000 AMU, as determined bygel permeation chromatography (GPC) using polystyrene standards. Withinthis range, the number average molecular weight may preferably be atleast about 10,000 AMU, more preferably at least about 30,000 AMU, yetmore preferably at least about 45,000 AMU. Also within this range, thenumber average molecular weight may preferably be up to about 300,000AMU, more preferably up to about 200,000 AMU, yet more preferably up toabout 150,000 AMU.

The molecular weight distribution of the hydrogenated block copolymer asmeasured by GPC is not particularly limited. The copolymer may have anyratio of weight average molecular weight to number average molecularweight.

Some of these hydrogenated block copolymers have a hydrogenatedconjugated diene polymer chain to which crystallinity is ascribed.Crystallinity of the hydrogenated block copolymer can be determined bythe use of a differential scanning calorimeter (DSC), for example,DSC-II Model manufactured by Perkin-Elmer Co. Heat of fusion can bemeasured by a heating rate of, for example, 10° C./min in an inert gasatmosphere such as nitrogen. For example, a sample may be heated to atemperature above an estimated melting point, cooled by decreasing thetemperature at a rate of 10° C./min, allowed to stand for about 1minute, and then heated again at a rate of 10° C./min.

The hydrogenated block copolymer may have any degree of crystallinity.In view of a balance of mechanical strength of the resulting resincomposition, those hydrogenated block copolymers having a melting pointof about −40° C. to about 200° C. or having no definite melting point(i.e., having non-crystallinity), as measured according to theabove-described technique, are preferred. More preferably, thehydrogenated block copolymers have a melting point of at least about 0°C., yet more preferably at least about 20° C., still more preferably atleast about 50° C.

The hydrogenated block copolymer may have any glass transitiontemperature (T_(g)) ascribed to the hydrogenated conjugated dienepolymer chain. From the standpoint of low-temperature impact strength ofthe resulting resin composition, it preferably has a T_(g) of up toabout 0° C., more preferably up to about −120° C. The glass transitiontemperature of the copolymer can be measured by the aforesaid DSC methodor from the visco-elastic behavior toward temperature change as observedwith a mechanical spectrometer.

Particularly preferred hydrogenated block copolymers are thestyrene-(ethylene-butylene) diblock andstyrene-(ethylene-butylene)-styrene triblock copolymers obtained byhydrogenation of styrene-butadiene and styrene-butadiene-styrenetriblock copolymers, respectively.

Suitable hydrogenated block copolymers include those commerciallyavailable as, for example, KRATON® G1650, G1651, and G1652 availablefrom Kraton Polymers, and TUFTECO® H1041, H1043, H1052, H1062, H1141,and H1272 available from Asahi Chemical. Preferred hydrogenated blockcopolymers include the highly hydrogenatedstyrene-(ethylene-butylene)-styrene triblock copolymers commerciallyavailable as, for example, TUFTEC® H1043 from Asahi Chemical.

The compatibilizer may be a partially hydrogenated block copolymer of analkenyl aromatic compound and a conjugated diene compound (“partiallyhydrogenated block copolymer”). The partially hydrogenated blockcopolymer is similar to the hydrogenated block copolymer describedabove, but varies in its degree of hydrogenation. The partiallyhydrogenated block copolymer is preferably hydrogenated to such a degreethat 20% to about 80% of the unsaturated bonds in the aliphatic chainmoiety derived from the conjugated diene remain unreduced. Within thisrange, the percentage of unreduced unsaturated bonds is preferably atleast 30%, more preferably at least 35%. Also within this range, thepercentage of unreduced unsaturated bonds is preferably up to about 70%,more preferably up to about 65%.

Preferred partially hydrogenated block copolymers include theselectively hydrogenated block copolymers in which the hydrogenationselectively reduces pendant aliphatic unsaturation resulting from 1,2-and 3,4-incorporation of the diene while effecting less reduction of thein-chain aliphatic unsaturation resulting from 1,4-incorporation of thediene. For example, in-chain aliphatic unsaturation may remain at leastabout 30 percent unhydrogenated, preferably at least about 40 percentunhydrogenated, more preferably at least about 50 percentunhydrogenated; and pendant aliphatic unsaturation remains up to about20 percent unhydrogenated, preferably up about 10 percentunhydrogenated, more preferably up to about 5 percent unhydrogenated. Inone embodiment, the ratio of the percentage of unhydrogenated in-chainaliphatic unsaturation to the percentage of unhydrogenated pendantaliphatic unsaturation is at least about 2, preferably at least about 5,more preferably at least about 10.

The partially hydrogenated block copolymer may be synthesized by blockpolymerization followed by hydrogenation as described, for example, inU.S. Pat. No. 4,994,508 to Shiraki et al. Suitable partiallyhydrogenated block copolymers include thestyrene-(butadiene-butylene)-styrene triblock copolymers commerciallyavailable from Asahi Chemical as, for example, TUFTEC® P-seriescopolymers. Additional description of partially hydrogenated blockcopolymers may be found in U.S. Patent Application Publication No.2003-0036602 A1 to Adedeji et al.

The compatibilizer may be a polyolefin-poly(alkenyl aromatic) copolymer.This copolymer may be, for example, a random copolymer, a blockcopolymer (including, for example, diblock copolymers, multiblockcopolymers, and radial teleblock copolymer), a graft copolymer, or acombination thereof. The polyolefin-poly(alkenyl aromatic) copolymer maybe added during formation of the first intimate blend, the secondintimate blend, or both. It is preferably added during formation of thefirst intimate blend. When the polyolefin-poly(alkenyl aromatic)copolymer is added during formation of both the first intimate blend andthe second intimate blend, about 1% to about 99% of the totalpolyolefin-poly(alkenyl aromatic) copolymer may be added as a componentof the first intimate blend, with the remainder added as a component ofthe second intimate blend.

In a preferred embodiment, the polyolefin-poly(alkenyl aromatic)copolymer comprises a polypropylene-polystyrene graft copolymer. Thepolypropylene-polystyrene graft copolymer is herein defined as a graftcopolymer having a propylene polymer backbone and one or more styrenepolymer grafts.

The propylene polymer material that forms the backbone or substrate ofthe polypropylene-polystyrene graft copolymer is (a) a homopolymer ofpropylene; (b) a random copolymer of propylene and an olefin selectedfrom the group consisting of ethylene and C₄-C₁₀ olefins, provided that,when the olefin is ethylene, the polymerized ethylene content is up toabout 10 weight percent, preferably up to about 4 weight percent, andwhen the olefin is a C₄-C₁₀ olefin, the polymerized content of theC₄-C₁₀ olefin is up to about 20 weight percent, preferably up to about16 weight percent; (c) a random terpolymer of propylene and at least twoolefins selected from the group consisting of ethylene and C₄-C₁₀alpha-olefins, provided that the polymerized C₄-C₁₀ alpha-olefin contentis up to about 20 weight percent, preferably up to about 16 weightpercent, and, when ethylene is one of the olefins, the polymerizedethylene content is up to about 5 weight percent, preferably up to about4 weight percent; or (d) a homopolymer or random copolymer of propylenewhich is impact-modified with an ethylene-propylene monomer rubber inthe reactor as well as by physical blending, the ethylene-propylenemonomer rubber content of the modified polymer being about 5 to about 30weight percent, and the ethylene content of the rubber being about 7 toabout 70 weight percent, and preferably about 10 to about 40 weightpercent. The C₄-C₁₀ olefins include the linear and branched C₄-C₁₀alpha-olefins such as, for example, 1-butene, 1-pentene,3-methyl-1-butene, 4-methyl-1-pentene, 1-hexene, 3,4-dimethyl-1-butene,1-heptene, 1-octene, 3-methyl-hexene, and the like. Propylenehomopolymers and impact-modified propylene homopolymers are preferredpropylene polymer materials. Although not preferred, propylenehomopolymers and random copolymers impact modified with anethylene-propylene-diene monomer rubber having a diene content of about2 to about 8 weight percent also can be used as the propylene polymermaterial. Suitable dienes include dicyclopentadiene, 1,6-hexadiene,ethylidene norbornene, and the like.

The term “styrene polymer”, used in reference to the grafted polymerpresent on the backbone of propylene polymer material in thepolypropylene-polystyrene graft copolymer, denotes (a) homopolymers ofstyrene or of an alkyl styrene having at least one C₁-C₄ linear orbranched alkyl ring substituent, especially a p-alkyl styrene; (b)copolymers of the (a) monomers with one another in all proportions; and(c) copolymers of at least one (a) monomer with alpha-methyl derivativesthereof, e.g., alpha-methylstyrene, wherein the alpha-methyl derivativeconstitutes about 1 to about 40% of the weight of the copolymer.

The polypropylene-polystyrene graft copolymer will typically compriseabout 10 to about 90 weight percent of the propylene polymer backboneand about 90 to about 10 weight percent of the styrene polymer graft.Within these ranges, the propylene polymer backbone may preferablyaccount for at least about 20 weight percent, of the total graftcopolymer; and the propylene polymer backbone may preferably account forup to about 40 weight percent of the total graft copolymer. Also withinthese ranges, the styrene polymer graft may preferably account for atleast about 50 weight percent, more preferably at least about 60 weightpercent, of the total graft copolymer.

The preparation of polypropylene-polystyrene graft copolymers isdescribed, for example, in U.S. Pat. No. 4,990,558 to DeNicola, Jr. etal. Suitable polypropylene-polystyrene graft copolymers are alsocommercially available as, for example, P1045H1 and P1085H1 from Basell.

The compatibilizer may be a polyolefin-poly(arylene ether) graftcopolymer. In one embodiment, the polyolefin forms the backbone and thepoly(arylene ether) the grafts of the graft copolymer. In anotherembodiment, the poly(arylene ether) forms the backbone and thepolyolefin the grafts of the graft copolymer. Included are copolymers inwhich a divalent linking group is used to join the polyolefin andpoly(arylene ether) chains. Suitable polyolefin-poly(arylene ether)graft copolymers include, for example, the polyphenyleneether-graft-polyethylene copolymers described in U.S. Pat. No. 3,522,326of Bostick et al., the polyolefin-graft/link-poly(arylene ether)copolymer described in U.S. Pat. No. 5,124,410 to Campbell, and thepolyolefin-graft-polyphenylene ether copolymers described in U.S. Pat.No. 4,876,310 to Bartmann.

The compatibilizer may be a polyolefin-poly(arylene ether) blockcopolymer. The polyolefin-poly(arylene ether) block copolymer comprisesat least one polyolefin block and at least one poly(arylene ether)block. In one embodiment, two blocks may be covalently joined by adivalent link. Suitable polyolefin-poly(arylene ether) block copolymersinclude those having divalent imide or amide links as described in U.S.Pat. No. 5,262,477 to Kasai et al., and thepolyolefin-link-polyphenylene ether copolymers in which the linkinggroup is derived from a polyolefin-terminal carboxylic acid, acidanhydride, epoxy, amine, alkoxysilyl, or sulfonic acid group asdescribed in JP 06-287367 A to Tomita et al.

The compatibilizer may be present in an amount of about 0.5 to about 30weight percent, based on the total weight of the composition. Withinthis range, the compatibilizer amount may preferably be at least about 1weight percent, more preferably at least about 2 weight percent. Alsowithin this range, the compatibilizer amount may preferably be up toabout 25 weight percent, more preferably up to about 20 weight percent,even more preferably up to about 15 weight percent. In one embodiment,all of the compatibilizer is added during formation of the firstintimate blend. In another embodiment, a portion, preferably more thanhalf, of the compatibilizer is added during formation of the firstintimate blend, and the remainder, preferably less than half, is addedduring formation of the second intimate blend.

The method comprises melt blending the first intimate blend and apolyolefin to form a second intimate blend. The polyolefin may be ahomopolymer or copolymer having at least about 80 weight percent ofunits derived from polymerization of ethylene, propylene, butylene, or amixture thereof. Examples of polyolefin homopolymers includepolyethylene, polypropylene, and polybutylene. Examples of polyolefincopolymers include random, graft, and block copolymers of ethylene,propylene, and butylene with each other, and further comprising up to 20weight percent of units derived from C₅-C₁₀ alpha olefins (excludingaromatic alpha-olefins). Polyolefins further include blends of the abovehomopolymers and copolymers. Preferred polyolefins may have a flexuralmodulus of at least about 100,000 pounds per square inch (psi) at 23° C.as measured according to ASTM D790. Suitable polyolefins are maycomprise, for example, the linear low density polyethylene availablefrom ExxonMobil as LL-6201, the low density polyethylene available fromExxonMobil as LMA-027, the high density polyethylene available fromExxonMobil as HD-6605, the ultra-high molecular weight polyethyleneavailable as Type 1900 from Montell Polyolefins, and the polybutylene(polybutene-1) available as PB0110 from Montell Polyolefins.

Presently preferred polyolefins include propylene polymers. Thepropylene polymer may be a homopolymer of polypropylene. Alternatively,the propylene polymer may be a random, graft, or block copolymer ofpropylene and at least one olefin selected from ethylene and C₄-C₁₀alpha-olefins (excluding aromatic alpha-olefins), with the proviso thatthe copolymer comprises at least about 80 weight percent, preferably atleast about 90 weight percent, of repeating units derived frompropylene. Blends of such propylene polymers with a minor amount ofanother polymer such as polyethylene are also included within the scopeof propylene polymers. The propylene polymer may have a melt flow indexof about 0.1 to about 50 g/10 min, preferably about 1 to about 30 g/10min when measured according to ASTM D1238 at 2.16 kg and 200° C. Theabove-described propylene polymers can be produced by various knownprocesses. Commercially available propylene polymers may also beemployed.

Preferred propylene polymers include homopolypropylenes. Highlypreferred propylene polymers include homopolypropylenes having acrystalline content of at least about 20%, preferably at least about30%. Suitable isotactic polypropylenes are commercially available as,for example, PD403 pellets from Basell (formerly Montell Polyolefins ofNorth America).

The composition may comprise polyolefin in an amount of about 10 toabout 80 weight percent, preferably about 10 to about 70 weight percent,more preferably about 10 to about 60 weight percent, based on the totalweight of the composition. In one embodiment, all of the polyolefin isadded during formation of the second intimate blend. In anotherembodiment, a portion of the polyolefin, preferably less than half, isadded during formation of the first intimate blend, and the remainder,preferably more than half, is added during formation of the secondintimate blend.

The thermoplastic composition is substantially free of at least onecomponent selected from (a) an unhydrogenated block copolymer of analkenyl aromatic compound and a conjugated diene, and (b) a poly(alkenylaromatic) resin. The term “substantially free” is herein defined asconstituting less than 0.5 weight percent, preferably less than 0.1weight percent, more preferably 0 weight percent, of the totalcomposition. While the composition is substantially free of at least oneof these components, it may contain one but not the other. Thus, in oneembodiment, the composition comprises an unhydrogenated block copolymerof an alkenyl aromatic compound and a conjugated diene (referred tohereinafter as an “unhydrogenated block copolymer”), and it issubstantially free of a poly(alkenyl aromatic) resin. In anotherembodiment, the composition comprises a poly(alkenyl aromatic) resin,and it is substantially free of an unhydrogenated block copolymer.

When the method comprises adding a poly(alkenyl aromatic) resin, it maybe added during formation of the first intimate blend, or the secondintimate blend, or both. Preferably, the poly(alkenyl aromatic) resin isadded during formation of the first intimate blend. The term“poly(alkenyl aromatic) resin” as used herein includes polymers preparedby methods known in the art including bulk, suspension, and emulsionpolymerization, which contain at least 25% by weight of structural unitsderived from an alkenyl aromatic monomer of the formula

wherein R¹ is hydrogen, C₁-C₈ alkyl, halogen, or the like; Z is vinyl,halogen, C₁-C₈ alkyl, or the like; and p is 0 to 5. Preferred alkenylaromatic monomers include styrene, chlorostyrenes such asp-chlorostyrene, vinyltoluenes such as p-vinyltoluene, and the like. Thepoly(alkenyl aromatic) resins include homopolymers of an alkenylaromatic monomer; random copolymers of an alkenyl aromatic monomer, suchas styrene, with one or more different monomers such as acrylonitrile,butadiene, alpha-methylstyrene, ethylvinylbenzene, divinylbenzene andmaleic anhydride; and rubber-modified poly(alkenyl aromatic) resinscomprising blends and/or grafts of a rubber modifier and a homopolymerof an alkenyl aromatic monomer (as described above), wherein the rubbermodifier may be a polymerization product of at least one C₄-C₁₀nonaromatic diene monomer, such as butadiene or isoprene, and whereinthe rubber-modified poly(alkenyl aromatic) resin comprises about 98 toabout 70 weight percent of the homopolymer of an alkenyl aromaticmonomer and about 2 to about 30 weight percent of the rubber modifier.Within these ranges it may be preferred to use at least about 88 weightpercent of the homopolymer of an alkenyl aromatic monomer. It may alsobe preferred to use up to about 94 weight percent of the homopolymer ofan alkenyl aromatic monomer. It may also be preferred to use at leastabout 6 weight percent of the rubber modifier. It may also be preferredto use up to about 12 weight percent of the rubber modifier.

The stereoregularity of the poly(alkenyl aromatic) resin may be atacticor syndiotactic. Highly preferred poly(alkenyl aromatic) resins includeatactic and syndiotactic homopolystyrenes. Suitable atactichomopolystyrenes are commercially available as, for example, EB3300 fromChevron, and P1800 from BASF. Suitable syndiotactic homopolystyrenes arecommercially available, for example, under the tradename QUESTRA® (e.g.,QUESTRA® WA550) from Dow Chemical Company. Highly preferred poly(alkenylaromatic) resins further include the rubber-modified polystyrenes, alsoknown as high-impact polystyrenes or HIPS, comprising about 88 to about94 weight percent polystyrene and about 6 to about 12 weight percentpolybutadiene, with an effective gel content of about 10% to about 35%.These rubber-modified polystyrenes are commercially available as, forexample, GEH 1897 from General Electric Plastics, and BA 5350 fromChevron.

When the composition comprises the poly(alkenyl aromatic) resin, it maybe present in an amount of about 1 to about 46 weight percent,preferably about 3 to about 46 weight percent, based on the total weightof the composition.

Alternatively, the amount of poly(alkenyl aromatic) resin, when present,may be expressed as a fraction of the total of poly(arylene ether) andpoly(alkenyl aromatic) resin based on the combined weight ofpoly(arylene ether) and poly(alkenyl aromatic) resin. The first intimateblend may comprise preferably comprise poly(alkenyl aromatic) resin inan amount of about 10 to about 80 weight percent, based on the combinedweight of poly(arylene ether) and poly(alkenyl aromatic) resin. Withinthis range, it may be preferred to use at least about 20 weight percent,more preferably at least about 40 weight percent, of the poly(alkenylaromatic) resin based on the total of the poly(arylene ether) and thepoly(alkenyl aromatic) resin. Also within this range, it may bepreferred to use up to about 70 weight percent, more preferably up toabout 65 weight percent of the poly(alkenyl aromatic) resin based on thetotal of the poly(arylene ether) and the poly(alkenyl aromatic) resin.The proportions of poly(alkenyl aromatic) resin and poly(arylene ether)may be manipulated to control the glass transition temperature (T_(g))of the single phase comprising these two components relative to theT_(g) of the poly(arylene ether) alone, or relative to the meltingtemperature (T_(m)) of the polyolefin alone. For example, the relativeamounts of poly(alkenyl aromatic) resin and poly(arylene ether) may bechosen so that the poly(arylene ether) and the poly(alkenyl aromatic)resin form a single phase having a glass transition temperature at leastabout 20° C. greater, preferably at least about 30° C. greater, than theglass transition temperature of the poly(alkenyl aromatic) resin alone,which may be, for example, about 100° C. to about 110° C. Also, therelative amounts of poly(alkenyl aromatic) resin and poly(arylene ether)may be chosen so that the poly(arylene ether) and the poly(alkenylaromatic) resin form a single phase having a glass transitiontemperature up to about 15° C. greater, preferably up to about 10° C.greater, more preferably up to about 1° C. greater, than the T_(m) ofthe polyolefin alone. The relative amounts of poly(alkenyl aromatic)resin and poly(arylene ether) may be chosen so that the poly(aryleneether) and the poly(alkenyl aromatic) resin form a single phase having aglass transition temperature of about 130° C. to about 180° C.

In one embodiment, the composition comprises an unhydrogenated blockcopolymer. When the composition comprises an unhydrogenated blockcopolymer, it may be added during formation of the first intimate blend,or the second intimate blend, or both. Preferably, the unhydrogenatedblock copolymer is added during formation of the first intimate blend.The unhydrogenated block copolymer is a copolymer comprising (A) atleast one block derived from an alkenyl aromatic compound and (B) atleast one block derived from a conjugated diene, in which the aliphaticunsaturated group content in the block (B) has not been reduced byhydrogenation. The alkenyl aromatic compound (A) and the conjugateddiene (B) are defined in detail above in the description of thehydrogenated block copolymer. The arrangement of blocks (A) and (B)includes a linear structure and a so-called radial teleblock structurehaving a branched chain.

Preferred of these structures are linear structures embracing diblock(A-B block), triblock (A-B-A block or B-A-B block), tetrablock (A-B-A-Bblock), and pentablock (A-B-A-B-A block or B-A-B-A-B block) structuresas well as linear structures containing 6 or more blocks in total of Aand B. More preferred are diblock, triblock, and tetrablock structures,with the A-B-A triblock structure being particularly preferred.

The unhydrogenated block copolymer may comprise about 10 to about 90weight percent of the (A) blocks. Within this range, it may be preferredto use at least about 20 weight percent (A) blocks. Also within thisrange, it may be preferred to use up to about 80 weight percent (A)blocks.

Particularly preferred unhydrogenated block copolymers includedstyrene-butadiene-styrene triblock copolymers.

Suitable unhydrogenated block copolymers may be prepared by knownmethods or obtained commercially as, for example, KRATON® D seriespolymers, including KRATON® D 1101 and D1102, from Kraton Polymers.

When present, the unhydrogenated block copolymer may be used at about 1to about 20 weight percent, preferably about 1 to about 15 weightpercent, more preferably about 1 to about 10 weight percent, based onthe total weight of the composition.

The method may, optionally, further comprise the addition of anethylene/alpha-olefin elastomeric copolymer. The alpha-olefin componentof the copolymer may be at least one C₃-C₁₀ alpha-olefin. Preferredalpha-olefins include propylene, 1-butene, and 1-octene. The elastomericcopolymer may be a random copolymer having about 25 to about 75 weightpercent, preferably about 40 to about 60 weight percent, ethylene andabout 75 to about 25 weight percent, preferably about 60 to about 40weight percent, alpha-olefin. Within these ranges, it may be preferredto use at least about 40 weight percent ethylene; and it may bepreferred to use up to about 60 weight percent ethylene. Also withinthese ranges, it may be preferred to use at least about 40 weightpercent alpha-olefin; and it may be preferred to use up to about 60weight percent alpha-olefin. The ethylene/alpha-olefin elastomericcopolymer may typically have a melt flow index of about 0.1 to about 20g/10 min at 2.16 kg and 200° C., and a density of about 0.8 to about 0.9g/ml.

Particularly preferred ethylene/alpha-olefin elastomeric copolymerrubbers include ethylene-propylene rubbers, ethylene-butene rubbers,ethylene-octene rubbers, and the like, and mixtures thereof.

The ethylene/alpha-olefin elastomeric copolymer may be preparedaccording to known methods or obtained commercially as, for example, theneat ethylene-propylene rubber sold as VISTALON® 878 by ExxonMobilChemical and the ethylene-butylene rubber sold as EXACT® 4033 byExxonMobil Chemical. Ethylene/alpha-olefin elastomeric copolymers mayalso be obtained commercially as blends in polypropylene as, forexample, the ethylene-propylene rubber pre-dispersed in polypropylenesold as product numbers Profax 7624 and Profax 8023 from Basell, and theethylene-butene rubber pre-dispersed in polypropylene sold as CatalloyK021P from Basell.

In one embodiment, the ethylene/alpha-olefin elastomeric copolymer maybe added during formation of the first intimate blend. In anotherembodiment, the ethylene/alpha-olefin elastomeric copolymer may be addedduring formation of the second intimate blend. In yet anotherembodiment, about 1 to about 99% of the ethylene/alpha-olefinelastomeric copolymer may be added during formation of the firstintimate blend, with the remainder added during formation of the secondintimate blend. In still another embodiment, the ethylene/alpha-olefinelastomeric copolymer may be prepared as a heterophasic copolymer withthe polyolefin, and the resulting heterophasic copolymer comprisingethylene/alpha-olefin elastomeric copolymer and polyolefin may be addedduring formation of the first intimate blend, or, preferably, duringformation of the second intimate blend.

When present, the ethylene/alpha-olefin elastomeric copolymer may beused in an amount of about 1 to about 20 weight percent, based on thetotal of the composition. Within this range, the ethylene/alpha-olefinelastomeric copolymer may preferably be used in an amount of at leastabout 3 weight percent. Also within this range, ethylene/alpha-olefinelastomeric copolymer may preferably be used in an amount up to about 15weight percent.

In one embodiment, the amount of ethylene/alpha-olefin elastomericcopolymer may be expressed as a fraction of the total of polyolefin andethylene/alpha-olefin elastomeric copolymer. Thus, when theethylene/alpha-olefin elastomeric copolymer is present, its amount maybe expressed as about 1 to about 60 weight percent, preferably about 10to about 40 weight percent, based on the combined weight of polyolefinand ethylene/alpha-olefin elastomeric copolymer.

The method may, optionally, comprise the addition of one or morereinforcing fillers. Reinforcing fillers may include, for example,inorganic and organic materials, such as fibers, woven fabrics andnon-woven fabrics of the E-, NE-, S-, T- and D-type glasses and quartz;carbon fibers, including poly(acrylonitrile) (PAN) fibers, vapor-growncarbon fibers, and especially graphitic vapor-grown carbon fibers havingaverage diameters of about 3 to about 500 nanometers (see, for example,U.S. Pat. Nos. 4,565,684 and 5,024,818 to Tibbetts et al., U.S. Pat. No.4,572,813 to Arakawa; U.S. Pat. Nos. 4,663,230 and 5,165,909 to Tennent,4,816,289 to Komatsu et al., U.S. Pat. No. 4,876,078 to Arakawa et al.,U.S. Pat. No. 5,589,152 to Tennent et al., and U.S. Pat. No. 5,591,382to Nahass et al.); potassium titanate single-crystal fibers, siliconcarbide fibers, boron carbide fibers, gypsum fibers, aluminum oxidefibers, asbestos, iron fibers, nickel fibers, copper fibers,wollastonite fibers; and the like. The reinforcing fillers may be in theform of glass roving cloth, glass cloth, chopped glass, hollow glassfibers, glass mat, glass surfacing mat, and non-woven glass fabric,ceramic fiber fabrics, and metallic fiber fabrics. In addition,synthetic organic reinforcing fillers may also be used including organicpolymers capable of forming fibers. Illustrative examples of suchreinforcing organic fibers are poly(ether ketone), polyimidebenzoxazole, poly(phenylene sulfide), polyesters, aromatic polyamides,aromatic polyimides or polyetherimides, acrylic resins, and poly(vinylalcohol). Fluoropolymers such as polytetrafluoroethylene, may be used.Also included are natural organic fibers known to one skilled in theart, including cotton cloth, hemp cloth, and felt, carbon fiber fabrics,and natural cellulosic fabrics such as Kraft paper, cotton paper, andglass fiber containing paper. Such reinforcing fillers could be in theform of monofilament or multifilament fibers and could be used eitheralone or in combination with another type of fiber, through, forexample, coweaving or core-sheath, side-by-side, orange-type or matrixand fibril constructions or by other methods known to one skilled in theart of fiber manufacture. They may be in the form of, for example, wovenfibrous reinforcements, non-woven fibrous reinforcements, or papers.

Preferred reinforcing fillers include glass fibers. Preferred glassfibers may have diameters of about 2 to about 25 micrometers, morepreferably about 10 to about 20 micrometers, yet more preferably about13 to about 18 micrometers. The length of the glass fibers may be about0.1 to about 20 millimeters, more preferably about 1 to about 10millimeters, yet more preferably about 2 to about 8 millimeters. Glassfibers comprising a sizing to increase their compatibility with thepolyolefin are particularly preferred. Suitable sizings are described,for example, in U.S. Pat. No. 5,998,029 to Adzima et al. Suitable glassfibers are commercially available as, for example, product numbers147A-14P (14 micrometer diameter) and 147A-17P (17 micrometer diameter)from Owens Corning.

Preferred reinforcing fillers further include talc. There are noparticular limitations on the physical characteristics of the talc.Preferred talcs may have an average particle size of about 0.5 to about25 micrometers. Within this range, it may be preferred to use a talchaving an average particle size up to about 10 micrometers, morepreferably up to about 5 micrometers. For some uses of the composition,it may be preferred to employ a talc that is F.D.A. compliant (i.e.,compliant with U.S. Food and Drug Administration regulations). Suitabletalcs include, for example, the F.D.A. compliant talc having an averageparticle size of about 3.2 micrometers sold as CIMPACT® 610(C) fromLuzenac. Preferred reinforcing fillers further include mica.

Preferred reinforcing fillers further include organoclays. As usedherein, an organoclay is a layered silicate clay, derived from layeredminerals, in which organic structures have been chemically incorporated.Illustrative examples of organic structures are trimethyldodecylammoniumion and N,N′-didodecylimidazolium ion. Since the surfaces of claylayers, which have a lattice-like arrangement, are electrically charged,they are capable of binding organic ions. There is no limitation withrespect to the layered minerals employed in this invention other thanthat they are capable of undergoing an ion exchange with the organicions. Preferred organoclays include layered minerals that have undergonecation exchange with organocations and/or onium compounds. Illustrativeof such layered minerals are the kaolinite group, the montmorillonitegroup, and the illite group which can include hydromicas, phengite,brammallite, glaucomite, celadonite and the like. Preferred layeredminerals include those often referred to as 2:1 layered silicateminerals like muscovite, vermiculite, saponite, hectorite andmontmorillonite, wherein montmorillonite is often preferred. The layeredminerals described above may be synthetically produced. However, mostoften they are naturally occurring and commercially available.Organoclays and their preparation are described, for example, in U.S.Pat. Nos. 4,569,923, 4,664,842, 5,110,501, and 5,160,454 to Knudson, Jr.et al.; U.S. Pat. Nos. 5,530,052 and 5,773,502 to Takekoshi et al.; U.S.Pat. No. 5,780,376 to Gonzales et al.; U.S. Pat. No. 6,036,765 to Farrowet al.; U.S. Pat. No. 6,228,903 B1 to Beall et al.; and U.S. Pat. No.6,262,162 B1 to Lan et al.

Combinations of any of the foregoing reinforcing fillers arecontemplated. When present, the reinforcing filler may used in an amountof about 1 to about 70 weight percent, based on the total weight of thecomposition. Within this range, the reinforcing filler amount maypreferably be at least about 5 weight percent. Also within this range,the reinforcing filler amount may preferably be up to about 60 weightpercent, more preferably up to about 50 weight percent.

The compatibility of the reinforcing filler and the polyolefin may beimproved not just with sizings on the surface of the reinforcingfillers, but also by adding to the composition a graft copolymercomprising a polyolefin backbone and polar grafts formed from one ormore cyclic anhydrides. The graft copolymer comprising a polyolefinbackbone and polar grafts formed from one or more cyclic anhydrides mayalso be useful in the absence of a reinforcing filler. It may be addedduring formation of the first intimate blend, the second intimate blend,or both. Such materials include graft copolymers of polyolefins andC₄-C₁₂ cyclic anhydrides, such as, for example, those available fromExxonMobil under the tradename EXXELOR® and from DuPont under thetradename FUSABOND®. Examples of suitable polyolefin-graft-cyclicanhydride copolymers are the polypropylene-graft-maleic anhydridematerials supplied by ExxonMobil as EXXELOR® PO1020 and by DuPont asFUSABOND® M613-05. Suitable amounts of such materials, when present, maybe readily determined and are generally about 0.1 to about 10 weightpercent, based on the total weight of the composition. Within thisrange, a polyolefin-graft-cyclic anhydride copolymer amount of at leastabout 0.5 weight percent may be preferred. Also within this range, apolyolefin-graft-cyclic anhydride copolymer amount of up to about 5weight percent may be preferred.

The one or more reinforcing fillers may be melt blended with the firstintimate blend and the polyolefin during formation of the secondintimate blend. Alternatively, the method may comprise an additionalblending step in which the one or more reinforcing fillers are blendedwith the second intimate blend. In another alternative, it may beadvantageous to add the reinforcing fillers, especially particulatefillers (i.e., those having an aspect ratio less than about 3), duringformation of the first intimate blend.

The method may, optionally, comprise the addition of additives to thecomposition. Such additives may include, for example, stabilizers, moldrelease agents, processing aids, flame retardants, drip retardants,nucleating agents, UV blockers, dyes, pigments, particulate fillers(i.e., fillers having an aspect ratio less than about 3), antioxidants,anti-static agents, blowing agents, and the like. Such additives arewell known in the art and appropriate amounts may be readily determined.There is no particular limitation on how or when the additives areadded. For example, the additives may be added during formation of thefirst intimate blend. Alternatively, the additives may be added duringformation of the second intimate blend. In another alternative, theadditives may be added in a separate step following formation of thesecond intimate blend.

As the composition is defined as comprising multiple components, it willbe understood that each component is chemically distinct, particularlyin the instance that a single chemical compound may satisfy thedefinition of more than one component.

One embodiment is a method of preparing a thermoplastic composition,comprising: melt-blending about 10 to about 70 weight percent of apoly(arylene ether) and about 0.5 to about 30 weight percent of acompatibilizer to form a first intimate blend; and melt-blending thefirst intimate blend and about 10 to about 80 weight percent of apolyolefin to form a second intimate blend; wherein the thermoplasticcomposition is substantially free of at least one component selectedfrom (a) an unhydrogenated block copolymer of an alkenyl aromaticcompound and a conjugated diene, and (b) a poly(alkenyl aromatic) resin;and wherein all weight percents are based on the total weight of thecomposition.

Another embodiment is a method of preparing a thermoplastic composition,comprising: melt-blending about 10 to about 70 weight percent of apoly(2,6-dimethyl-1,4-phenylene ether), apoly(2,6-dimethyl-1,4-phenylene ether-co-2,3,6-trimethyl-1,4-phenyleneether), or a mixture thereof, and about 0.5 to about 30 weight percentof a styrene-(ethylene-butylene)-styrene triblock copolymer to form afirst intimate blend; and melt-blending the first intimate blend andabout 10 to about 80 weight percent of a homopolypropylene to form asecond intimate blend; wherein the thermoplastic composition issubstantially free of at least one component selected from (a) anunhydrogenated block copolymer of an alkenyl aromatic compound and aconjugated diene, and (b) a poly(alkenyl aromatic) resin; and whereinall weight percents are based on the total weight of the composition.

Another embodiment is a method of preparing a thermoplastic composition,comprising: melt blending a poly(arylene ether) and a compatibilizer toform a first intimate blend; and melt blending the first intimate blendand a polyolefin to form a thermoplastic composition consistingessentially of the poly(arylene ether), the compatibilizer, and thepolyolefin. In this embodiment, the phrase “consisting essentially of”will be understood as excluding an amount of an additional componentthat substantially degrades a physical property of the composition. Forexample, it would exclude an amount of an additional component thatreduces by more than 5% an objective measure of the composition'sstiffness (e.g., flexural modulus measured at 25° C. according to ASTMD79), impact strength (e.g., notched or unnotched Izod impact strengthmeasured at 25° C. according to ASTM D256), heat resistance (e.g., heatdistortion temperature in ° C. measured according to ASTM D658), or blowmoldability (e.g., hang time measured using 2.5 inch diameter low workscrew with 24:1 ratio of parison length to outer diameter, a singlecardioid head design, a step mold, a screw speed of 25 rotations perminute (rpm), a die gap of 35%, a blow air pressure of 80 psi, and amold temperature of 80° C.). The percent change in an objective propertyvalue is measured in comparison to a corresponding composition withoutthe additional component. In particular, the addition of an amount ofblock copolymer of an alkenyl aromatic compound and a conjugated dieneto this composition would be expected to substantially decrease thecomposition's flexural modulus and tensile modulus. The addition of anamount of homopolystyrene would be expected to substantially decreasethe heat distortion temperature and dispersed phase softeningtemperature.

Another embodiment is a method of preparing a thermoplastic composition,comprising: melt blending a poly(arylene ether), a poly(alkenylaromatic) resin, and a compatibilizer to form a first intimate blend;and melt blending the first intimate blend, and a polyolefin to form athermoplastic composition consisting essentially of the poly(aryleneether), the poly(alkenyl aromatic) resin, the compatibilizer, and thepolyolefin. As above, the phrase “consisting essentially of” will beunderstood as excluding an amount of an additional component thatsubstantially degrades a physical property of the composition.

Another embodiment is a method of preparing a thermoplastic composition,comprising: melt blending a poly(arylene ether), an unhydrogenated blockcopolymer of an alkenyl aromatic compound and a conjugated diene, and acompatibilizer to form a first intimate blend; and melt blending thefirst intimate blend, and a polyolefin to form a thermoplasticcomposition consisting essentially of the poly(arylene ether), theunhydrogenated block copolymer of an alkenyl aromatic compound and aconjugated diene, the compatibilizer, and the polyolefin. As above, thephrase “consisting essentially of” will be understood as excluding anamount of an additional component that substantially degrades a physicalproperty of the composition.

Another embodiment is a thermoplastic composition prepared according toany of the above-described methods.

While the method has been described in terms of poly(aryleneether)-polyolefin blends, it is generally applicable to a wide varietyof thermoplastic blends in which a stiffer (e.g., higher flexuralmodulus) polymer is to be dispersed in the matrix of a less stiff (e.g.,lower flexural modulus) polymer to produce blends having consistentlyreproducible properties. Furthermore, while the method has beendescribed in terms of upstream and downstream addition of componentsduring a single extruder pass, the first and second intimate blends maybe formed in separate passes. For example, the poly(arylene ether), thecompatibilizer, and optional components may be added to an extruder toform a first intimate blend that is extruded into strands andpelletized. This pelletized first intimate blend may then be added to anextruder in a second pass, with downstream addition of the polyolefinand additional optional components to form the second intimate blend.

The method is particularly useful for thermoplastic blends comprising atleast three components, where the first component is intended to formthe matrix phase of the final blend, the second component is intended tobe a dispersed phase, and the third component is intended to reside atleast partially at the interface of the matrix phase and the dispersedphase. Thus, the method may comprise: melt-blending to form a firstintimate blend comprising a dispersed phase component and an interfacialcomponent; and melt-blending to form a second intimate blend comprisingthe first intimate blend and a matrix component.

The invention is further illustrated by the following non-limitingexamples.

EXAMPLES 1-4, COMPARATIVE EXAMPLES 1, 2

Five formulations were compounded by various methods in a twin screwextruder. The components of the formulation are summarized in Table 1.The formulations and compounding methods are summarized in Table 2.

General Blending/Compounding Procedure: Using quantities specified inTable 1, components to be added upstream were hand mixed in a bag. Theresulting mixture was subsequently mixed aggressively with a mechanicalblender for uniformity. The uniform mixture was subsequently fed througha feeder and entered into an extruder at the extruder initial entrypoint. Downstream components were added at barrel 6 of a 10-barrelextruder.

General Extrusion: a 30 millimeter co-rotating twin-screw extruder wasused. Blends were melt extruded at 520° F., 450-500 rpm, and athroughput rate of 30-50 pounds per hour. Melt from the extruder wasforced through a three-hole die to produce melt strands. These strandswere rapidly cooled by passing them through a cold-water bath. Thecooled strands were chopped into pellets. Pellets were dried in an ovenat 200° F. for 2-4 hours.

General Molding: ASTM parts were molded on a 120 tonne molding machine(manufacturer Van Dorn) at 450-550° F. barrel temperature and 100-120°F. mold temperature.

Parts were tested according to ASTM methods. Izod notched impact wasmeasured at 23° C. according to ASTM D256. Heat distortion temperature(HDT) was measured at 66 psi and 264 psi on ⅛ inch samples according toASTM D648. Flexural modulus and flexural strength were measured at 23°C. on ⅛ inch samples according to ASTM D790. Tensile strength at yield,tensile strength at break, and tensile elongation at break were measuredat 23° C. according to ASTM D638. Where presented, standard deviationsreflect measurements on three samples for heat distortion temperaturemeasurements, and for five samples for other tests.

Results of property measurements are presented in Table 2. The resultsshow that the Example 1 composition, consisting of poly(arylene ether),polypropylene, and styrene-(ethylene-butylene)-styrene copolymer,exhibits higher flexural modulus, higher flexural strength, higher heatdistortion temperatures, and higher tensile strengths than theComparative Example 1 composition that additionally compriseshomopolystyrene and a styrene-butadiene-styrene block copolymer. TheExample 1 composition, which was blended using downstream addition ofpolypropylene, also exhibits higher flexural modulus, higher flexuralstrength, and higher tensile strength at break than Comparative Example2, which used upstream addition of polypropylene. The Example 2composition, consisting of poly(arylene ether), polypropylene,styrene-(ethylene-butylene)-styrene copolymer, and homopolystyrene,exhibits higher flexural modulus, higher flexural strength, higher heatdistortion temperatures, and higher tensile strengths than theComparative Example 1 composition that additionally comprises astyrene-butadiene-styrene block copolymer. The Example 3 composition,consisting of poly(arylene ether), polypropylene,styrene-(ethylene-butylene)-styrene copolymer, andstyrene-butadiene-styrene triblock copolymer exhibits higher heatdistortion temperatures and higher tensile strengths than theComparative Example 1 composition that additionally compriseshomopolystyrene. The Example 4 composition, in which polypropyleneaddition was split upstream and downstream, exhibits higher notched andunnotched Izod impact strengths, and higher tensile strength at yieldthan Comparative Example 2, which used upstream addition ofpolypropylene. TABLE 1 material abbreviation Description PPhomopolypropylene, obtained as D-015-C2 from Sunoco Chemicals SEBSstyrene-(ethylene-butadiene)-styrene copolymer, 66 weight percentpolystyrene, and obtained as TUFTEC ® H1043 from Asahi PPEpoly(2,6-dimethyl-1,4-phenylene ether), IV = 0.46 dl/g, obtained fromGeneral Electric Company SBS styrene-butadiene-styrene block copolymer,obtained as KRATON ® D1101 from Kraton Polymers xPS homopolystyrene,obtained as PP-738 from Huntsman Chemical, MFI = 10.5 g/10 min at 200°C., 5 kg

TABLE 2 Ex. 1 Ex. 2 Ex. 3 C. Ex. 1 Ex. 4 C. Ex. 2 upstream componentsPPE 50 20 40 15 50 50 xPS — 30 — 25 — — SEBS 10 10 10 10 10 10 SBS — —10 10 — — PP — — — — 20 40 downstream components PP 40 40 40 40 20 —properties flex. mod., 23° C., 243729 ± 432  274872 ± 1138 203940 ± 2844215292 ± 511  241143 ± 1464 240795 ± 793  ⅛ in. (psi) flex. strength atyield 8569 ± 23 9754 ± 52 7205 ± 69 7161 ± 59 8429 ± 69  8424 ± 108(psi) HDT at 66 psi (° C.) 291.9 ± 1.2 236.0 ± 1.8 270.6 ± 4.3 211.04 ±1.5  288.3 ± 2.2 294.0 ± 5.8 HDT at 264 psi (° C.) 201.9 ± 4.4 195.7 ±1.4 172.1 ± 0.6 169.3 ± 0.5 196.6 ± 3.6 197.8 ± 2.7 notched Izod, 23° C. 1.4 ± 0.1  0.4 ± 0.0  1.7 ± 0.1  1.9 ± 0.1  1.9 ± 0.1  1.3 ± 0.1(ft-lb/in) unnotched Izod, 23° C.  36.6 ± 4.8  20.3 ± 3.7 no break nobreak no break  39.9 ± 2.6 (ft-lb/in) tensile strength at yield, 6108 ±67 7006 ± 37 5202 ± 10 5114 ± 14 6150 ± 23 6065 ± 45 23° C. (psi)tensile strength at break, 5972 ± 85 4950 ± 63 4928 ± 85 4064 ± 41  5574± 253 5770 ± 57 23° C. (psi) tensile elongation at break,  25.7 ± 2.6 58.2 ± 12.1  37.4 ± 4.4  93.7 ± 6.7  46.5 ± 14.9  31.7 ± 2.0 23° C. (%)

While the invention has been described with reference to a preferredembodiment, it will be understood by those skilled in the art thatvarious changes may be made and equivalents may be substituted forelements thereof without departing from the scope of the invention. Inaddition, many modifications may be made to adapt a particular situationor material to the teachings of the invention without departing from theessential scope thereof. Therefore, it is intended that the inventionnot be limited to the particular embodiment disclosed as the best modecontemplated for carrying out this invention, but that the inventionwill include all embodiments falling within the scope of the appendedclaims.

All cited patents, patent applications, and other references areincorporated herein by reference in their entirety.

1. A method of preparing a thermoplastic composition, comprising:melt-blending about 10 to about 70 weight percent of a poly(aryleneether), and about 0.5 to about 30 weight percent of a compatibilizer toform a first intimate blend; and melt-blending the first intimate blend,and about 10 to about 80 weight percent of a polyolefin to form a secondintimate blend; wherein the thermoplastic composition is substantiallyfree of at least one component selected from (a) an unhydrogenated blockcopolymer of an alkenyl aromatic compound and a conjugated diene, and(b) a poly(alkenyl aromatic) resin; and wherein all weight percents arebased on the total weight of the composition.
 2. The method of claim 1,wherein the melt-blending to form a first intimate blend comprisesheating to a temperature of about 180° C. to about 400° C.
 3. The methodof claim 1, wherein the melt-blending to form a first intimate blendcomprises mixing with at least two mixing elements.
 4. The method ofclaim 1, wherein the melt-blending to form a first intimate blend andthe melt-blending to form a second intimate blend collectively comprisemixing with a mixing energy input of at least about 0.20 kW-hr/kg. 5.The method of claim 1, wherein the first intimate blend furthercomprises a polyolefin in an amount not greater than that of thepolyolefin added during formation of the second intimate blend.
 6. Themethod of claim 1, wherein the poly(arylene ether) comprises a pluralityof structural units of the formula:

wherein for each structural unit, each Q¹ is independently halogen,primary or secondary C₁-C₈ alkyl, phenyl, C₁-C₈ haloalkyl, C₁-C₈aminoalkyl, C₁-C₈ hydrocarbonoxy, or C₂-C₈ halohydrocarbonoxy wherein atleast two carbon atoms separate the halogen and oxygen atoms; and eachQ² is independently hydrogen, halogen, primary or secondary C₁-C₈ alkyl,phenyl, C₁-C₈ haloalkyl, C₁-C₈ aminoalkyl, C₁-C₈ hydrocarbonoxy, orC₂-C₈ halohydrocarbonoxy wherein at least two carbon atoms separate thehalogen and oxygen atoms.
 7. The method of claim 6, wherein each Q¹ isindependently C₁-C₄ alkyl or phenyl, and each Q² is independentlyhydrogen or methyl.
 8. The method of claim 1, wherein the poly(aryleneether) has an intrinsic viscosity of about 0.2 to about 0.6 dL/g asmeasured in chloroform at 25° C.
 9. The method of claim 1, wherein thepoly(arylene ether) comprises a copolymer of 2,6-dimethylphenol and2,3,6-trimethylphenol.
 10. The method of claim 1, wherein thecompatibilizer comprises a hydrogenated block copolymer of an alkenylaromatic compound and a conjugated diene compound.
 11. The method ofclaim 10, wherein the hydrogenated block copolymer comprises: (A) atleast one block derived from an alkenyl aromatic compound having theformula

wherein R² and R³ each represent a hydrogen atom, a C₁-C₈ alkyl group,or a C₂-C₈ alkenyl group; R⁴ and R⁸ each represent a hydrogen atom, aC₁-C₈ alkyl group, a chlorine atom, or a bromine atom; and R⁵-R⁷ eachindependently represent a hydrogen atom, a C₁-C₈ alkyl group, or a C₂-C₈alkenyl group, or R⁴ and R⁵ are taken together with the central aromaticring to form a naphthyl group, or R⁵ and R⁶ are taken together with thecentral aromatic ring to form a naphthyl group; and (B) at least oneblock derived from a conjugated diene, in which the aliphaticunsaturated group content in the block (B) is reduced by hydrogenation.12. The method of claim 10, wherein the hydrogenated block copolymer ishydrogenated to such a degree that less than 20% of the aliphaticunsaturation derived from the conjugated diene remains unreduced. 13.The method of claim 10, wherein the hydrogenated block copolymer has analkenyl aromatic content of about 10 to about 90 weight percent.
 14. Themethod of claim 10, wherein the hydrogenated block copolymer has analkenyl aromatic content of about 50 to about 90 weight percent.
 15. Thethermoplastic composition of claim 10, wherein the hydrogenated blockcopolymer comprises a styrene-(ethylene-butylene)-styrene triblockcopolymer.
 16. The thermoplastic composition of claim 10, wherein thehydrogenated block copolymer comprises a styrene-(ethylene-butylene)diblock copolymer.
 17. The method of claim 1, wherein the compatibilizercomprises a polyolefin-poly(alkenyl aromatic) copolymer selected frompolyolefin-poly(alkenyl aromatic) graft copolymers,polyolefin-poly(alkenyl aromatic) diblock copolymers,polyolefin-poly(alkenyl aromatic) multiblock copolymers,polyolefin-poly(alkenyl aromatic) radial block copolymers, and mixturesthereof.
 18. The method of claim 17, wherein the polyolefin-poly(alkenylaromatic) copolymer comprises a polypropylene-polystyrene graftcopolymer comprising about 50 to about 85 weight percent of a propylenepolymer backbone and about 15 to about 50 weight percent of one or morestyrene polymer grafts.
 19. The method of claim 1, wherein thepolyolefin comprises a homopolymer or copolymer having at least about 80weight percent of units derived from polymerization of ethylene,propylene, butylene, or a mixture thereof.
 20. The method of claim 1,wherein the polyolefin is a propylene polymer comprising a homopolymerof polypropylene; or a random, graft, or block copolymer of propyleneand at least one olefin selected from ethylene and C₄-C₁₀ alpha-olefins;with the proviso that the copolymer comprises at least about 80 weightpercent of repeating units derived from propylene.
 21. The method ofclaim 1, wherein the polyolefin comprises a homopolypropylene.
 22. Themethod of claim 1, wherein the first intimate blend further comprisesabout 1 to about 20 weight percent of an unhydrogenated block copolymerof an alkenyl aromatic compound and a conjugated diene compound; whereinthe unhydrogenated block copolymer comprises a styrene-butadiene diblockcopolymer or a styrene-butadiene-styrene triblock copolymer.
 23. Themethod of claim 1, wherein the first intimate blend further comprisesabout 1 to about 20 weight percent of an unhydrogenated block copolymerof an alkenyl aromatic compound and a conjugated diene compound.
 24. Themethod of claim 23, wherein the wherein the unhydrogenated blockcopolymer comprises a styrene-butadiene diblock copolymer or astyrene-butadiene-styrene triblock copolymer.
 25. The method of claim 1,wherein the first intimate blend and/or the second intimate blendfurther comprises a reinforcing filler.
 26. The method of claim 1,wherein the first intimate blend and/or the second intimate blendfurther comprises an additive selected from stabilizers, mold releaseagents, processing aids, flame retardants, drip retardants, nucleatingagents, UV blockers, dyes, pigments, antioxidants, antistatic agents,and combinations comprising at least one of the foregoing additives. 27.The method of claim 1, wherein wherein the poly(arylene ether) comprisesa poly(2,6-dimethyl-1,4-phenylene ether), apoly(2,6-dimethyl-1,4-phenylene ether-co-2,3,6-trimethyl-1,4-phenyleneether), or a mixture thereof; wherein the compatibilizer comprises astyrene-(ethylene-butylene)-styrene triblock copolymer; wherein thepolyolefin comprises a homopolypropylene; and wherein the thermoplasticcomposition is substantially free of at least one component selectedfrom (a) an unhydrogenated block copolymer of an alkenyl aromaticcompound and a conjugated diene, and (b) a poly(alkenyl aromatic) resin.28. A method of preparing a thermoplastic composition, comprising: meltblending a poly(arylene ether) and a compatibilizer to form a firstintimate blend; and melt blending the first intimate blend and apolyolefin to form a thermoplastic composition consisting essentially ofthe poly(arylene ether), the compatibilizer, and the polyolefin.